Harry h



H. H. STYLL.

LENS.

APPLICATION FILED DEC. Ii. I936.

1,267,821 Patented May 28,1918.

A T ORNE V5 8, LL? HQMJJWWW HARRY H. STYLL, 0F SOUTHBRIDGE, MASSACHUSETTS.

LENS.

Specification of Letters Patent.

"Patented May 28, 1918.

Application filed December 11, 1916. Serialhfo. 138;241.

lenses sndhas particular rcfcrenceto an improved construction of lens blank for a bifocal lens, and an improved process or method of construction of the lens to secure the mostsatisfsetory results and minimize diiliculties previously experienced in the con .struction of the same.

One of the leading objectsof my present invention is the revision of an improved construction of bi ocal lens blank which Hilly be readily produced in commercially marketable form. and which shall be so constructed as to facilitate the manufacture of the blank into a finishcdlens andminimize'losses. due to slipping or displacement of the Segment- :portion of non-integral or two-piece bifoesls during the manufacturing operation.

A further object of my present invention is'the provision of aconstructionin which the segment may be laterally reinforeedto prevent any tendency of some to slip at the edgos-during'thc grinding or finishing operation. V n V Other objects and advantages of my improved construction and process of producing bifocal lenses shouldbe readily apparent by reference to thefollowing specification taken in connection with the accompanying drawings, and it'will be understood that I may make any'medifications in the specific details of construction shown and described within the scope of the nppcnded clsinis withoutdeparting from orexcceding the spirit of my invention- Figurel represents a plan iew of a blank embodying one form of my improvement.

represents a similar view of e. modified construction. 7 V V V Fig. III represents sseetionel view taken on the line HIT-III of 7 Fig. IV representse similar View taken onthe IVIV*of Figll.

Fig. .Vrepresentse sectional new illustrating another modifiedconstruction.

Fig. Vl'represents a. sectional View of another modification. 7 V

:Fig. VII represents a plan View of a.

lens cut from the style of blank illustrated in Fig. I, the blank from which the lens out being shown'in dotted line.

Fig. VIII represents a YlBW of it slightly modifiedconstruction of finished lens cinbodying my improvement.

In the drawings, in which similar charactors of reference arecniployed to denote corresponding parts throughout the several views, theelumerul 1 designates the major portion of the blank having formed therein the countersink 2 adopted to receive the se ment 3, which has the curved lower face adapted to'fit the counter sink and ii slight surrounding Wztll l, the portion 'inelosed by the wall 4 in practice having to be ground away in theproduction ofthe finished lens, ttS indicated bythe dotted lines inFig. V.

The constructionj not described hsshitherto bee-n employed in the art in connection with the construction of fused bifocal lenses or lenses in which the ports are brought to a temperature sufficient to cause them to melt and How together, becoming a single integral or. homogeneous construction but has not hitherto been employed in connection with What may be termed the cement type of lens, that to. say the type of lens in which theparts l and 3 are separate from each other and are united by means of a cement or other adhesive medium so that they remain distinct and may be scpsr L" one from the other if desired.

In the case of lenses in which the arts are fused. together it has been possib e to satisfactorily grind the two-part blank, since on account of their uniting by fusion there is no possibility of relative shifting movement of the segment and major blank. but so for as I am aware rior toiny invention no one has conceive the possibility of so securing the segment Within the recess :thntit would be possible tosinlilarly grind a bifocal in which the parts were not integral. n

I have discovered, however, thstfhy the use of my improvement it is possible to satisfactorily produce lenses of this charsscter. One of the essential features of my intention, therefore. consists. in so securing or connecting the ports that there will be some means in additionto the connecting content for preventing lateral. slipping or relntive shifting movement of the blank and segment during theigiinding operation.

11 Figs. I and I I have illust-rtted one form of construction for attaining this result, in which I have shown as drilled through coinciding portions of the segment and major blank, the apertures or sockets 5, adapted to receive a suitable hardened plug or looking member (3, which may be in the form of a cement, amalgam or other substance, which will key or connect the two parts together and prevent relative lateral movement during the twisting or compound rubbing movements which are given to the lens while the surface is being ground thereon.

In Figs. II and IV, I have illustrated another form of my invention in which the segment is disposed with a portion overhanging the edge of the lens and has the lateral recesses 7 formed therein to provide the central dove-tail 8, a suitable cementitious locking medium or the like 9 being secured to the edge of the main blank 1 and having portions projecting and fitting up into the recesses 7 and interlocking with the dove-tail 8 to mechanically retain the dovetail.

Indicated in Figs. II and IV in dotted lines, as capable of use in conjunction with the structure there illustrated, if desired, and specifically illustrated in the sectional view Fig. VI, is a further possible modification of my invention in which the tapered annulus 10 is employed encircling the proj ecting portion of the segment and engaging the major blank 1 so that the lateral edges of the segment will be braced during the entire grinding operation, the bracing member 10 being gradually worn away with the segment. This form possesses additional advantages, in that the glass of the segment is laterally braced and any tendency of the segment to chip off during the grinding is thus prevented and an extremely satisfactory invisible line of joinder between the major blank and segment thus assured.

Fig. V represents another form of the invention, in which this same result is similarly obtained. In Fig. V, however, in place of employing the additional bracing device 10, I form the countersink in the blank 1 with a slight surrounding wall 11, a superfluous quantity of cement being placed in the countersink as the segment is applied thereto to fill in any existing space between the edge of the segment and the wall of the countersink. In this way the entire glass is ground away simultaneously to the posi tion indicated in the dotted lines, Fig. V, the glass of the major blank itself holding the segment against sliding and reinforcing to prevent any possible chipping.

Fig. VII illustrates the cutting of the completed lens from my improved blank, and it will be noted that the bottom line of the ordinary or usual shape of lens falls in such position as to cut off that portion of the blank in which the apertures or sockets 5 have been formed so that no trace remains on the finished lens of the manner in which the segment was held and at the same time the segment has ben satisfactorily held durin the entire formation of the lens and all lia ility of slipping prevented.

From the foregoing description taken in connection with the accompanying drawings, the construction of my improved lens blank and the advantages possessed thereby, as well as the complete process of forming the lens, should be readily understood, and it will be seen that my improved lens blank embodies the pair of pieces of glass generally of different indices of refraction as has been commonly employed in the art, but which pieces of glass in place of being fused or permanently united one to the other, are detachably connected through the medium of a suitable cement, and are in addition mechanically locked against lateral movement, and that the blank thus put out may be ground and finished to the best advantage and may in fact be handled in any way in which it is possible to handle an ordinary fused lens blank without liability of relative displacement of the parts, while it will also be noted in conjunction with several forms of my invention illustrated that I laterally brace the projecting segment and thus eliminate the liability of chipping and the necessity of grinding down to quite thin form, and thus considerably reducing the size of the effective segment as sometimes occurs at present, even with the fused types of lens in which no lateral brace is provided for the projecting segment.

In connection with the necessity and util ity of my present invention I would call particular attention to the fact that the best known cement which may be employed for the satisfactory unitin 1 of the two parts of a lens, such as the bi ocal illustrated, and which will have the proper retaining power, coefficient of expansion, transparency and the like, are cements or adhesives having a relatively low melting point, this melting point ordinarily being a great deal lower than the melting or softening point of the pitch or material commonly employed in securing the lens to the binding block. It is well known among lens grinders, however, that in the grinding and particularly in the polishing of an optical lens considerable care must be taken to keep the lens sufficiently lubricated so that the friction between the polishing or grinding tool and the lens will not heat the lens to a degree which will loosen it from the pitch, and if this care is not taken the lens will become so heated as to become loosened from the pitch and slip around on the block or fly 01f therefrom. Consequently it would be impossible on account of this heating effect to polish either the plain or the bifocal side of my improved blank without very great probability that the parts would become so heated that the adhesive would be softened and serve as a lubricant, enhancing the sliding tendency of the segment rather than preventing it from slidin As efore stated, it is, therefore, the primary purpose of my present invention to prevent this sliding or relative movement of the parts which is accomplished either by a mechanical lock or by the use of a supplemental cement or adhesive having a considerably higher softening point than that of either the cement which is intended to permanently unite the parts, or of the pitch or other substance used to retain the lens on the block. This cement may for example be a condensite or bakelite or similar product, serving to lock or retain the parts in desired relative relation one to the other, but being so disposed that this second locking medium will be cut away or removed and will not be present in the finished lens.

It will be understood that if desired, however, to pern'ianently reinforce the lens, the plugs or other locking members, such as sticks for example, may be so disposed as to remain on the lens, but preferably adjacent the edge thereof, as indicated in Fig. VIII, to permanently assist in holding the parts, this, however, being a mere detail in the final cutting of the finished lens.

I claim:

1. An optical lens blank, including a major portion having a countersink, a segment having a portion fitting Within the countersink, and a portion extending thercabove, and means for laterally bracing the projecting portion of the segment.

2. A blank for a two-part bifocal lens, comprising a major portion, a segment removably secured thereto, mechanical means for locking the parts against relative movement, and means laterally engaging the edge of the segment for preventing chipping thereof during the grinding operation.

3. An optical lens blank, comprising a major portion and a supplemental portion, a cementitious medium interposed between and uniting the parts, and a second cementitious medium having a higher melting point than the first engaging both of the parts for locking the same against accidental relative movement.

4:. A blank for a two part bifocal lens, comprising a major portion and a segment, a transparent cementitious medium interposed between and uniting the parts, and a second cementitious medium of considerably higher melting point than the first engaging and additionally uniting the parts.

5. A blank for a two part bifocal lens, comprising a major portion and a segment, a transparent cementitious medium interposed between and uniting the parts, a second cemcntitious medium of considerably higher melting point than the first engaging and additionally uniting the parts, said second cementitious medium being disposed on the blank to lie outside the normal field of vision as respects the finished lens cut from the blank.

8. The combination With a lens blank including a major portion and a segment attached thereto and a portion of the segment projecting beyond the surface of the major portion, of means surrounding the projecting portion of the segment for laterally bracing the same during the grinding operation.

T. A lens blank comprising a major por tion and a segment, means for interlocking the segment with the major portion of the blank, and means surrounding the segment for laterally bracing the same against movement with respect to the major blank during the grinding operation.

In testimony whereof I aflix my signature in the presence of two Witnesses.

HARRY H. STYLL. Witnesses H. K. Pansons, Eorrn M. HALVORSEN,

Copies. of this patent may be obtained for live cents each, by addressing the Commissioner of intents, Washington, D. O." 

